From U.S. Pat. No. 6,272,427, it is known that, for otherwise like ambient conditions, a higher temperature of the intake air causes, inter alia, the following: a higher tendency to knock; an improved vaporization of the fuel; a reduced wall film formation of the fuel on the inner walls of the intake manifold; and, a reduction of the inducted air mass and therefore a reduction of the needed fuel quantity. In the context of this background, modern controls for internal combustion engines process the intake air temperature which can be measured by a corresponding sensor or is computed via a corresponding temperature model.
Space reasons in the vicinity of the internal combustion engine are the cause that sensors, with which the temperature of the intake air can be measured, cannot be mounted in the immediate vicinity of the combustion chamber of the internal combustion engine; instead, these sensors are, for example, mounted in the air filter housing, in an air mass sensor, in a throttle flap support or in combination with a sensor for measuring the air pressure in the intake manifold.
In its path into the combustion chamber through the intake manifold, the intake air can become warm on the warm walls of the intake manifold and on other warm or hot parts which lie in the flow path. For this reason, this means that the temperature, which is measured with these sensors, is usually less than the actual temperature of the fresh air, which is enclosed in the combustion chamber after the end of the intake stroke and is not yet mixed with the hot residual gas which possibly is present in the combustion chamber.
For this reason, U.S. Pat. No. 6,272,427 suggests a correction of the measured temperature of the intake air. For this purpose, a weighting factor is used which is computed by means of characteristic lines or characteristic fields in dependence upon the intake air temperature, the engine temperature and an operating point of the internal combustion engine.